According to a straight reading of evolutionary theory, an animal should plump for the physically fittest mate so that their offspring inherit the best possible mix of genes. But sexual attraction is a complicated affair.

A conference at London Zoo last year, called "Why do animals mate with the 'wrong' partner?", examined the various factors that can draw two animals together – and some ill-fated pairings. Here is a selection of the sexual adventures explored at the meeting. David Robson

Sexuality is a complex affair that can be shaped by both nature and nurture. Male Saanen goats that grow up without seeing a female are more likely to take a fancy to other males, compared with those reared with both sexes.